Description: At the present time, there are no binding rules of evidence or set of evidentiary principles to be applied in Senate impeachment trials. Rather, recourse is taken to the evidentiary rules and principles applicable in contemporaneous court proceedings and to precedents from past impeachment trial to provide guidance for Senate Impeachment Trial Committees or for the full Senate on evidentiary questions which arise in the impeachment context. This report compiles evidentiary precedents from the Senate impeachment trials of Judges Harry E. Claiborne, Halsted Ritter, Harold Louderback, and Charles Swayne. The evidentiary rulings and principles gleaned from this examination are arranged in subject matter categories, and within those categories, in reverse chronological order by trial.